mcp-server-code-runner

What it does

Code Runner executes code snippets across 40+ programming languages, including JavaScript, Python, Go, Rust, C#, Ruby, and PHP. The run-code tool accepts code as input and returns the output or runtime errors. Execution runs locally on your machine against installed interpreters and compilers.

Who it's for

Developers testing code snippets during work without leaving the editor or Claude—language explorers checking syntax and library behavior, and engineers prototyping algorithms for quick validation.

Common use cases

• Test a Python script or JavaScript snippet without switching to a terminal
• Verify regex patterns or string manipulations in multiple languages
• Explore unfamiliar language syntax or standard library APIs
• Debug algorithmic problems and see output in real time

Setup pitfalls

• Language interpreters and compilers must be in PATH. For example, python3, node, and go must be executable from the command line.
• Windows users may fail to connect with npx. Use bunx or the cmd workaround as documented in the README.
• Code executes with your full user permissions. Do not run untrusted code.